Within the scope of a vehicle speed controller, known speed control devices enable one to control the speed of one's own vehicle to a desired speed selected by the driver. Furthermore, advanced speed control devices are known, so-called ACC systems (adaptive cruise control), which are additionally in a position to find the position of a vehicle traveling ahead in one's own lane with the aid of a radar sensor or a comparable position-finding system, to measure its distance ahead and its relative speed, and then, by an intervention in the drive system and possibly also the braking system of one's own vehicle, to control the speed in such a way that the preceding vehicle is followed at an appropriately safe distance.
Within the scope of the speed control or distance control, if a setpoint/actual deviation occurs, a control strategy will be required which determines in which manner, and at which curve over time, the actual value should be brought back to the setpoint value. Parameters which determine this control strategy in a determinative way are, for example, the upper and the lower boundary values for the acceleration of one's own vehicle. The upper boundary value determines the maximum vehicle acceleration which is to be demanded of the drive system of the vehicle, within the scope of the control, and the (negative) lower boundary value determines the maximum deceleration at which the vehicle is to be decelerated. Other parameters may, for example, establish under what conditions an intervention in the braking system is to take place.
In the establishment of these parameters, various objectives should be considered which, in part, may be contradictory to one another. For one thing, of course, the necessary traffic safety should be ensured. In addition, a manner of travel should be achieved that is as comfortable as possible for the driver and the passengers, and which is also as fuel saving as possible. On the other hand, however, the flow of traffic should also not be impeded unnecessarily, and the system behavior should correspond to the greatest extent possible to the intuitive driving behavior of a human driver. If, for instance, a slower preceding vehicle is being followed on the passing lane of an expressway, and this vehicle then changes lanes to the right neighboring lane, one's own vehicle should then be accelerated again to the desired speed as quickly as possible, so that the passing procedure of one's own vehicle is shortened and the following traffic is not impeded. Up to this point, the establishment of the parameters determining the control strategy is based on a compromise between the various objectives.